Surgical instruments

ABSTRACT

An ultrasonic surgical instrument is disclosed including an ultrasonic blade, an ultrasonic transducer operably coupled to the ultrasonic blade, and a control circuit. The ultrasonic transducer is configured to transmit ultrasonic vibrations to the ultrasonic blade based on a drive signal. The control circuit is configured to provide the drive signal to the ultrasonic transducer, monitor a vibration frequency of the drive signal, and modify the drive signal based on a change in the vibration frequency of the drive signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application claiming priority under35 U.S.C. § 120 to U.S. patent application Ser. No. 15/257,385, entitledSURGICAL INSTRUMENTS, filed Sep. 6, 2016, now U.S. Patent ApplicationPublication No. 2017/0056056, which is a continuation applicationclaiming priority under 35 U.S.C. § 120 to U.S. patent application Ser.No. 13/923,954, entitled SURGICAL INSTRUMENTS, filed Jun. 21, 2013,which issued on Sep. 20, 2016 as U.S. Pat. No. 9,445,832, which is acontinuation application claiming priority under 35 U.S.C. § 120 to U.S.patent application Ser. No. 11/888,222, entitled SURGICAL INSTRUMENTS,filed Jul. 31, 2007, which issued on Aug. 20, 2013 as U.S. Pat. No.8,512,365, the entire disclosures of which are hereby incorporated byreference herein.

BACKGROUND

Ultrasonic instruments, including both hollow core and solid coreinstruments, are used for the safe and effective treatment of manymedical conditions. Ultrasonic instruments are advantageous because theymay be used to cut and/or coagulate organic tissue using energy in theform of mechanical vibrations transmitted to a surgical end effector atultrasonic frequencies. Ultrasonic vibrations, when transmitted toorganic tissue at suitable energy levels and using a suitable endeffector, may be used to cut, dissect, elevate or cauterize tissue or toseparate muscle tissue off bone. Such instruments may be used for openprocedures or minimally invasive procedures, such as endoscopic orlaparoscopic procedures, wherein the end effector is passed through atrocar to reach the surgical site.

Activating or exciting the end effector (e.g., cutting blade) of suchinstruments at ultrasonic frequencies induces longitudinal vibratorymovement that generates localized heat within adjacent tissue,facilitating both cutting and coagulation. Because of the nature ofultrasonic instruments, a particular ultrasonically actuated endeffector may be designed to perform numerous functions, including, forexample, cutting and coagulation.

Ultrasonic vibration is induced in the surgical end effector byelectrically exciting a transducer, for example. The transducer may beconstructed of one or more piezoelectric or magnetostrictive elements inthe instrument hand piece. Vibrations generated by the transducersection are transmitted to the surgical end effector via an ultrasonicwaveguide extending from the transducer section to the surgical endeffector. The waveguides and end effectors are designed to resonate atthe same frequency as the transducer. Therefore, when an end effector isattached to a transducer the overall system frequency is the samefrequency as the transducer itself.

The zero to peak amplitude of the longitudinal ultrasonic vibration atthe tip, d, of the end effector behaves as a simple sinusoid at theresonant frequency as given by:d=A sin(ωt)where:ω=the radian frequency which equals a times the cyclic frequency, f; andA=the zero-to-peak amplitude.The longitudinal excursion is defined as the peak-to-peak (p-t-p)amplitude, which is just twice the amplitude of the sine wave or 2A.

Ultrasonic surgical instruments may be divided into two types, singleelement end effector devices and multiple-element end effector devices.Single element end effector devices include instruments such as scalpelsand ball coagulators. Single-element end effector instruments havelimited ability to apply blade-to-tissue pressure when the tissue issoft and loosely supported. Sometimes, substantial pressure may benecessary to effectively couple ultrasonic energy to the tissue. Thisinability to grasp the tissue results in a further inability to fullycoapt tissue surfaces while applying ultrasonic energy, leading toless-than-desired hemostasis and tissue joining. In these cases,multiple-element end effectors may be used. Multiple-element endeffector devices, such as clamping coagulators, include a mechanism topress tissue against an ultrasonic blade that can overcome thesedeficiencies.

Although ultrasonic surgical instruments are widely used in manysurgical applications, their utility is limited by their inability toreact to tissue and end effector conditions. For example, as the endeffector of an ultrasonic instrument is used to coagulate and/or cuttissue, it often heats up. This may cause inconsistencies in theperformance of the instrument. Also, there is no way for a clinicianusing the instrument to know when the instrument has begun to coagulatetissue, when the instrument has begun to cut tissue, or any otherinformation about the tissue.

Another set of drawbacks of ultrasonic instruments stems from existingend effector designs. In the existing designs, only the tip of the endeffector (e.g., the blade) is ultrasonically active. Accordingly, tissuecontacting the blade more than a fraction of a wavelength from the tipmay not be affected at all. Further, because waves must propogate fromthe transducer to the tip of the end effector, existing end effectorsare not very flexible, limiting their ability to articulate andconsequently limiting their usefulness in laparoscopic and endoscopicsurgical applications.

SUMMARY

In one general aspect, the various embodiments are directed to asurgical device. The surgical device may comprise a transducer, an endeffector, a generator and a control circuit. The transducer may beconfigured to provide vibrations. The end effector may be coupled to thetransducer and may extend from the transducer along the longitudinalaxis. The generator may provide an electrical signal to the transducer.Also, the control circuit may modify a current amplitude of theelectrical signal in response to a change in a vibration frequency ofthe end effector. Accordingly to various embodiments, the controlcircuit may detect a first contribution to a vibration frequency of theend effector, the first contribution originating from tissue in contactwith the end effector. Also, according to various embodiments, thecontrol circuit may indicate a change in a vibration frequency of theend effector.

In another general aspect, the various embodiments are directed to asurgical instrument comprising a transducer, a clamping mechanism and acontrol circuit. The transducer may be configured to provide vibrations.The end effector may be coupled to the transducer and may extend fromthe transducer along the longitudinal axis. The clamping mechanism maybe translatable toward the end effector. The control circuit maycalculate a curve representing a coefficient of collagen denaturationover time. The coefficient of collagen denaturation may be calculatedconsidering: a power delivered by the end effector to a portion oftissue; a clamp force applied to the portion of tissue between the endeffector and the clamping mechanism; a displacement of the end effector;and a vibration frequency of the end effector. According to variousembodiments, the control circuit also may identify a first change in aslope of the curve from a substantially negative slope to asubstantially neutral slope and indicate a beginning of tissuecoagulation in response to the first change. Also, according to variousembodiments, the control circuit may identify a first region of thecurve having a substantially constant slope. The control circuit alsomay calculate a region property describing the first region and derive atissue property of the portion of tissue in contact with the endeffector.

In yet another general aspect, the various embodiments are directed to asurgical device comprising an end effector. The end effector maycomprise a central member extending longitudinally through the endeffector and a plurality of radial mode transducers. The radial modetransducers may be positioned around the central member, and may beconfigured to respond to an electrical signal by vibrating in adirection perpendicular to the longitudinal axis. The standing waves maybe ultrasonic.

In yet another general aspect, various embodiments are directed to anultrasonic surgical instrument that includes an ultrasonic blade, anultrasonic transducer operably coupled to the ultrasonic blade, and acontrol circuit. The ultrasonic transducer is configured to transmitultrasonic vibrations to the ultrasonic blade based on a drive signal.The control circuit is configured to provide the drive signal to theultrasonic transducer, monitor a vibration frequency of the drivesignal, and modify the drive signal based on a change in the vibrationfrequency of the drive signal.

In yet another general aspect, various embodiments are directed to anultrasonic surgical instrument including an ultrasonic transducer, anend effector, and a control circuit. The end effector includes a clamparm and an ultrasonic blade operably coupled to the ultrasonictransducer. The clamp arm is movable relative to the ultrasonic blade tocapture tissue. The control circuit is configured to provide a drivesignal to the ultrasonic transducer to cause the ultrasonic transducerto transmit ultrasonic vibrations to the ultrasonic blade, monitor avibration frequency of the drive signal, and modify the drive signalbased on a change in the vibration frequency of the drive signal.

In yet another general aspect, various embodiments are directed to anultrasonic surgical instrument including an ultrasonic transducer, anultrasonic blade operably coupled to the ultrasonic transducer, meansfor providing a drive signal to the ultrasonic transducer to cause theultrasonic transducer to transmit ultrasonic vibrations to theultrasonic blade, means for monitoring a vibration frequency of thedrive signal, and means for modifying the drive signal based on a changein the vibration frequency of the drive signal.

FIGURES

The novel features of the various embodiments are set forth withparticularity in the appended claims. The various embodiments, however,both as to organization and methods of operation, together with furtherobjects and advantages thereof, may best be understood by reference tothe following description, taken in conjunction with the accompanyingdrawings as follows.

FIG. 1 illustrates one embodiment of a surgical system including asurgical instrument and an ultrasonic generator.

FIG. 2 illustrates one embodiment of the surgical instrument shown inFIG. 1 .

FIG. 3 illustrates an exploded view of one embodiment the surgicalinstrument shown in FIG. 1 .

FIG. 4 illustrates one embodiment of a clamping mechanism that may beused with the surgical instrument shown in FIG. 1 .

FIG. 5 illustrates a cut-away view of one embodiment of the surgicalinstrument shown in FIG. 1 .

FIG. 6 illustrates various internal components of one embodiment of thesurgical instrument shown in FIG. 1 .

FIG. 7 illustrates one embodiment of a drive yoke of the surgicalinstrument shown in FIG. 1 .

FIG. 8 illustrates one embodiment of a drive collar of the surgicalinstrument shown in FIG. 1 .

FIG. 9 illustrates one embodiment of a surgical system including asurgical instrument having single element end effector.

FIG. 10 illustrates a block diagram of one embodiment of a surgicaldevice.

FIG. 11 shows a graph illustrating results of an example test of asurgical device.

FIG. 12 shows a graph illustrating a relationship between end effectorfrequency and end effector temperature.

FIG. 13 illustrates a block diagram of one embodiment of a surgicaldevice.

FIG. 14 shows a graph illustrating a coefficient of collagendenaturation curve.

FIG. 15 shows a graph illustrating a coefficient of collagendenaturation curve.

FIG. 16 shows a series of curves illustrating relationships between anormalized value of a first region of a coefficient of collagendenaturation curve and clamp force, power level, outside diameter andwall thickness.

FIG. 17 illustrates one embodiment of an end effector for a surgicaldevice including radial mode transducers.

FIG. 18 illustrates one embodiment of the end effector of FIG. 17installed on a surgical instrument including a clamp arm.

FIG. 19 illustrates one embodiment of the end effector of FIG. 17including a flexible central member.

FIG. 20 illustrates one embodiment of the end effector of FIG. 17including a transducer defining a concavity.

FIG. 21 illustrates one embodiment of the end effector of FIG. 20 .

DESCRIPTION

Before explaining the various embodiments in detail, it should be notedthat the embodiments are not limited in application or use to thedetails of construction and arrangement of parts illustrated in theaccompanying drawings and description. The illustrative embodiments maybe implemented or incorporated in other embodiments, variations andmodifications, and may be practiced or carried out in various ways. Forexample, the surgical instruments and blade configurations disclosedbelow are illustrative only and not meant to limit the scope orapplication thereof. Also, the blade and end effector designs describedhereinbelow may be used in conjunction with any suitable device.Furthermore, unless otherwise indicated, the terms and expressionsemployed herein have been chosen for the purpose of describing theillustrative embodiments for the convenience of the reader and are notto limit the scope thereof.

Examples of ultrasonic surgical instruments and blades are disclosed inU.S. Pat. Nos. 5,322,055 and 5,954,736, 6,309,400 B2, 6,278,218 B1,6,283,981 B1, and 6,325,811 B1, which are incorporated herein byreference in their entirety. These references disclose ultrasonicsurgical instrument designs and blade designs where a longitudinal modeof the blade is excited. The result is a longitudinal standing wavewithin the instrument. Accordingly, the instrument has nodes, where thetransverse motion is equal to zero, and anti-nodes, where the transversemotion is at its maximum. The instrument's tissue end effector is oftenpositioned at an anti-node to maximize its longitudinal motion.

Various embodiments will now be described to provide an overallunderstanding of the principles of the structure, function, manufacture,and use of the devices and methods disclosed herein. One or moreexamples of these embodiments are illustrated in the accompanyingdrawings. Those of ordinary skill in the art will understand that thedevices and methods specifically described herein and illustrated in theaccompanying drawings are non-limiting embodiments and that the scope ofthe various embodiments is defined solely by the claims. The featuresillustrated or described in connection with one embodiment may becombined with the features of other embodiments. Such modifications andvariations are intended to be included within the scope of the claims.

It will be appreciated that the terms “proximal” and “distal” are usedherein with reference to a clinician gripping a surgical device at itshand piece assembly, or other comparable piece. Thus, the end effectoris distal with respect to the more proximal hand piece assembly. It willbe further appreciated that, for convenience and clarity, spatial termssuch as “top” and “bottom” also are used herein with respect to theclinician gripping the hand piece assembly, or comparable piece.However, surgical instruments are used in many orientations andpositions, and these terms are not intended to be limiting and absolute.

FIG. 1 illustrates one embodiment of a surgical system including asurgical instrument and an ultrasonic generator. FIG. 2 illustrates oneembodiment of the apparatus shown in FIG. 1 . In the embodimentillustrated in FIGS. 1-2 , the surgical system 10 includes an ultrasonicclamp coagulator instrument 120 and an ultrasonic generator 30. Thesurgical instrument 120 includes an ultrasonic drive unit 50. As will befurther described, an ultrasonic transducer of the drive unit 50, and anultrasonic end effector 180 of the clamp instrument 120, togetherprovide an acoustic assembly of the surgical system 10, with theacoustic assembly providing ultrasonic energy for surgical procedureswhen powered by generator 30. It will be noted that, in someapplications, the ultrasonic drive unit 50 is referred to as a “handpiece assembly” because the surgical instrument 120 of the surgicalsystem 10 is configured such that a clinician grasps and manipulates theultrasonic drive unit 50 during various procedures and operations. Theinstrument 120 may include a scissors-like grip arrangement whichfacilitates positioning and manipulation of the instrument 120 apartfrom manipulation of the ultrasonic drive unit 50.

The generator 30 of the surgical system 10 sends an electrical signalthrough a cable 32 at a selected excursion, frequency, and phasedetermined by a control system of the generator 30. As will be furtherdescribed, the signal causes one or more piezoelectric elements of theacoustic assembly of the surgical instrument 120 to expand and contractalong a longitudinal axis, thereby converting the electrical energy intomechanical motion. The mechanical motion results in longitudinal wavesof ultrasonic energy that propagate through the acoustic assembly in anacoustic standing wave to vibrate the acoustic assembly at a selectedfrequency and excursion. The end effector 180 is placed in contact withtissue of the patient to transfer the ultrasonic energy to the tissue.For example, a distal portion of blade 180′ of the end effector may beplaced in contact with the tissue. As further described below, asurgical tool, such as, a jaw or clamping mechanism, may be utilized topress the tissue against the blade 180′.

As the end effector 180 couples with the tissue, thermal energy or heatis generated as a result of friction, acoustic absorption, and viscouslosses within the tissue. The heat is sufficient to break proteinhydrogen bonds, causing the highly structured protein (e.g., collagenand muscle protein) to denature (e.g., become less organized). As theproteins are denatured, a sticky coagulum forms to seal or coagulatesmall blood vessels. Deep coagulation of larger blood vessels resultswhen the effect is prolonged.

The transfer of the ultrasonic energy to the tissue causes other effectsincluding mechanical tearing, cutting, cavitation, cell disruption, andemulsification. The amount of cutting as well as the degree ofcoagulation obtained varies with the excursion of the end effector 180,the frequency of vibration, the amount of pressure applied by the user,the sharpness of the end effector 180, and the coupling between the endeffector 180 and the tissue.

In the embodiment illustrated in FIG. 1 , the generator 30 includes acontrol system integral with the generator 30, a power switch 34, and atriggering mechanism 36. The power switch 34 controls the electricalpower to the generator 30, and when activated by the triggeringmechanism 36, the generator 30 provides energy to drive the acousticassembly of the surgical system 10 frequency and to drive the endeffector 180 at a predetermined excursion level. The generator 30 drivesor excites the acoustic assembly at any suitable resonant frequency ofthe acoustic assembly.

When the generator 30 is activated via the triggering mechanism 36,electrical energy is continuously applied by the generator 30 to atransducer stack or assembly 40 of the acoustic assembly. A phase-lockedloop in the control system of the generator 30 monitors feedback fromthe acoustic assembly. The phase lock loop adjusts the frequency of theelectrical energy sent by the generator 30 to match the resonantfrequency of the selected longitudinal mode of vibration of the acousticassembly. In addition, a second feedback loop in the control systemmaintains the electrical current supplied to the acoustic assembly at apre-selected constant level in order to achieve substantially constantexcursion at the end effector 180 of the acoustic assembly.

The electrical signal supplied to the acoustic assembly will cause thedistal end of the end effector 180, e.g., the blade 180′, to vibratelongitudinally in the range of, for example, approximately 20 kHz to 250kHz. According to various embodiments, the blade 180′ may vibrate in therange of about 54 kHz to 56 kHz, for example, at about 55.5 kHz. Inother embodiments, the blade 180′ may vibrate at other frequenciesincluding, for example, about 31 kHz or about 80 kHz. The excursion ofthe vibrations at the blade can be controlled by, for example,controlling the amplitude of the electrical signal applied to thetransducer assembly 40 of the acoustic assembly by the generator 30.

As noted above, the triggering mechanism 36 of the generator 30 allows auser to activate the generator 30 so that electrical energy may becontinuously supplied to the acoustic assembly. The triggering mechanism36 may comprise a foot activating switch that is detachably coupled orattached to the generator 30 by a cable or cord. Alternatively, thetriggering mechanism can be configured as a hand switch incorporated inthe ultrasonic drive unit 50 to allow the generator 30 to be activatedby a user.

The generator 30 also has a power line 38 for insertion in anelectro-surgical unit or conventional electrical outlet. It iscontemplated that the generator 30 can also be powered by a directcurrent (DC) source, such as a battery. The generator 30 can compriseany suitable generator, such as Model No. GEN04, available from EthiconEndo Surgery, Inc.

In the embodiment illustrated in FIGS. 1 and 3 , the ultrasonic driveunit 50 of the surgical instrument includes a multi-piece housing 52adapted to isolate the operator from the vibrations of the acousticassembly. The drive unit housing 52 can be shaped to be held by a userin a conventional manner, but it is contemplated that the present clampcoagulator instrument 120 principally be grasped and manipulated by ascissors-like arrangement provided by a housing of the apparatus, aswill be described. While the multi-piece housing 52 is illustrated, thehousing 52 may comprise a single or unitary component.

The housing 52 of the ultrasonic drive unit 50 generally includes aproximal end, a distal end, and a cavity extending longitudinallytherein. The distal end of the housing 52 includes an opening 60configured to allow the acoustic assembly of the surgical system 10 toextend therethrough, and the proximal end of the housing 52 is coupledto the generator 30 by the cable 32. The cable 32 may include ducts orvents 62 to allow air or other fluids to be introduced into the housing52 of the ultrasonic drive unit 50 to cool the transducer assembly 40 ofthe acoustic assembly.

The housing 52 of the ultrasonic drive unit 50 may be constructed from adurable plastic, such as ULTEM®. It is also contemplated that thehousing 52 may alternatively be made from a variety of materialsincluding other plastics (e.g. liquid crystal polymer (LCP), nylon, orpolycarbonate) and/or metals (e.g., aluminum, steel, etc.). A suitableultrasonic drive unit 50 is Model No. HP054, available from Ethicon EndoSurgery, Inc.

The acoustic assembly of the surgical instrument generally includes afirst acoustic portion and a second acoustic portion. The first acousticportion may be carried by the ultrasonic drive unit 50, and the secondacoustic portion (in the form of an end effector 180, as will bedescribed) is carried by the ultrasonic clamp coagulator 120. The distalend of the first acoustic portion is operatively coupled to the proximalend of the second acoustic portion, preferably by a threaded connection.

In the embodiment illustrated in FIG. 2 , the first acoustic portionincludes the transducer stack or assembly 40 and a mounting device 84,and the second acoustic portion includes the end effector 180. The endeffector 180 may in turn comprise a transmission component, or waveguide181 (FIG. 3 ), as well as a distal portion, or blade 180′, forinterfacing with tissue.

The components of the acoustic assembly may be acoustically tuned suchthat the length of each component is an integral number of one-halfwavelengths (nλ/2), where the wavelength λ is the wavelength of apre-selected or operating longitudinal vibration frequency f₀ of theacoustic assembly, and n is any non-negative integer. It is alsocontemplated that the acoustic assembly may incorporate any suitablearrangement of acoustic elements.

The transducer assembly 40 of the acoustic assembly converts theelectrical signal from the generator 30 into mechanical energy thatresults in longitudinal vibratory motion of the end effector 180 atultrasonic frequencies. When the acoustic assembly is energized, avibratory motion standing wave is generated through the acousticassembly. The excursion of the vibratory motion at any point along theacoustic assembly depends on the location along the acoustic assembly atwhich the vibratory motion is measured. A minimum or zero crossing inthe vibratory motion standing wave is generally referred to as a node(e.g., where motion is usually minimal), and local absolute valuemaximum or peak in the standing wave is generally referred to as ananti-node. The distance between an anti-node and its nearest node isone-quarter wavelength (λ/4).

In the embodiment illustrated in FIG. 2 , the transducer assembly 40 ofthe acoustic assembly, which is also known as a “Langevin stack”,generally includes a transduction portion 90, a first resonator 92, anda second resonator 94. The transducer assembly 40 may be an integralnumber of one-half system wavelengths (nλ/2) in length. It is to beunderstood that other embodiments of the transducer assembly 40 maycomprise a magnetostrictive, electromagnetic or electrostatictransducer.

The distal end of the first resonator 92 is connected to the proximalend of transduction section 90, and the proximal end of the secondresonator 94 is connected to the distal end of transduction portion 90.The first and second resonators 92 and 94 may be fabricated fromtitanium, aluminum, steel, or any other suitable material, and mostpreferably, the first resonator 92 is fabricated from 303 stainlesssteel and the second resonator 94 is fabricated from 7075-T651 Aluminum.The first and second resonators 92 and 94 have a length determined by anumber of variables, including the length of the transduction section90, the speed of sound of material used in the resonators 92 and 94, andthe desired fundamental frequency f₀ of the transducer assembly 40. Thesecond resonator 94 can be tapered inwardly from its proximal end to itsdistal end to function as a velocity transformer and amplify theultrasonic vibration excursion.

The transduction portion 90 of the transducer assembly 40 may comprise apiezoelectric section of alternating positive electrodes 96 and negativeelectrodes 98, with the piezoelectric elements 100 alternating betweenthe electrodes 96 and 98. The piezoelectric elements 100 can befabricated from any suitable material, such as, for example, leadzirconate-titanate, lead metaniobate, lead titanate, or otherpiezoelectric material. Each of the positive electrodes 96, negativeelectrodes 98, and piezoelectric elements 100 have a bore extendingthrough the center. The positive and negative electrodes 96 and 98 areelectrically coupled to wires 102 and 104, respectfully. The wires 102and 104 transmit the electrical signal from the generator 30 to theelectrodes 96 and 98.

The piezoelectric elements 100 may be held in compression between thefirst and second resonators 92 and 94 by a bolt 106. The bolt 106 mayhave a head, a shank, and a threaded distal end. The bolt 106 may beinserted from the proximal end of the first resonator 92 through thebores of the first resonator 92, the electrodes 96 and 98, andpiezoelectric elements 100. The threaded distal end of the bolt 106 isscrewed into a threaded bore in the proximal end of second resonator 94.The bolt 106 may be fabricated from steel, titanium, aluminum, or othersuitable material. For example, the bolt 106 may be fabricated fromTi-6Al-4V Titanium, or from 4037 low alloy steel.

The piezoelectric elements 100 may be energized in response to theelectrical signal supplied from the generator 30 to produce an acousticstanding wave in the acoustic assembly. The electrical signal causes anelectromagnetic field across the piezoelectric elements 100, causing thepiezoelectric elements 100 to expand and contract in a continuous manneralong the longitudinal axis of the voltage gradient, producing highfrequency longitudinal waves of ultrasonic energy. The ultrasonic energyis transmitted through the acoustic assembly to the end effector 180.

The mounting device 84 of the acoustic assembly has a proximal end, adistal end, and may have a length substantially equal to an integralnumber of one-half system wavelengths (nλ/2). The proximal end of themounting device 84 may be axially aligned and coupled to the distal endof the second resonator 94 by an internal threaded connection near ananti-node. It is also contemplated that the mounting device 84 may beattached to the second resonator 94 by any suitable means, and thesecond resonator 94 and mounting device 84 may be formed as a single orunitary component.

The mounting device 84 is coupled to the housing 52 of the ultrasonicdrive unit 50 near a node. The mounting device 84 may include anintegral mounting flange 108 disposed around its periphery. The mountingflange 108 may be disposed in an annular groove 110 formed in thehousing 52 of the ultrasonic drive unit 50 to couple the mounting device84 to the housing 52. A compliant member or material 112, such as a pairof silicone rubber O-rings attached by stand-offs, may be placed betweenthe annular groove 110 of the housing 52 and the integral flange 108 ofthe mounting device 86 to reduce or prevent ultrasonic vibration frombeing transmitted from the mounting device 84 to the housing 52.

The mounting device 84 may be secured in a predetermined axial positionby a plurality of pins 114, for example, four. The pins 114 are disposedin a longitudinal direction ninety (90) degrees apart from each otheraround the outer periphery of the mounting device 84. The pins 114 arecoupled to the housing 52 of the ultrasonic drive unit 50 and aredisposed through notches in the acoustic mounting flange 108 of themounting device 84. The pins 114 may be fabricated from stainless steel.According to various embodiments, the pins 114 may be formed as integralcomponents of the housing 52.

The mounting device 84 may be configured to amplify the ultrasonicvibration excursion that is transmitted through the acoustic assembly tothe distal end of the end effector 180. In one embodiment, the mountingdevice 84 comprises a solid, tapered horn. As ultrasonic energy istransmitted through the mounting device 84, the velocity of the acousticwave transmitted through the mounting device 84 is amplified. It iscontemplated that the mounting device 84 be configured as any suitableshape, such as, for example, a stepped horn, a conical horn, anexponential horn, a unitary gain horn, or the like.

The mounting device 84 may be acoustically coupled to the secondacoustic portion of the ultrasonic clamp coagulator instrument 120. Thedistal end of the mounting device 84 may be coupled to the proximal endof the second acoustic portion by an internal threaded connection nearan anti-node, but alternative coupling arrangements can be employed.

FIG. 3 illustrates an exploded view of one embodiment of the surgicalinstrument shown in FIG. 1 . The proximal end of the ultrasonic clampcoagulator instrument 120 preferably receives and is fitted to thedistal end of the ultrasonic drive unit 50 by insertion of the driveunit 50 into the housing 52, as shown in FIG. 2 . The ultrasonic clampcoagulator instrument 120 may be attached to and removed from theultrasonic drive unit 50 as a unit. The ultrasonic clamp coagulator 120may be disposed of after a single use.

The ultrasonic clamp coagulator instrument 120 may include a handleassembly or a housing 130, which may comprise mating housing portions131, 132, and an elongated or endoscopic portion 150. When the presentapparatus is configured for endoscopic use, the construction can bedimensioned such that portion 150 has an outside diameter of about 5.5mm. The elongated portion 150 of the ultrasonic clamp coagulatorinstrument 120 may extend substantially orthogonally from the apparatushousing 130. The elongated portion 150 can be selectively rotated withrespect to the housing 130 as described below. The elongated portion 150may include an outer tubular member or sheath 160, an inner tubularactuating member 170, and the second acoustic portion of the acousticsystem in the form of an end effector 180 including a blade 180′. Aswill be described, the outer sheath 160, the actuating member 170, andthe end effector 180 may be joined together for indexed rotation as aunit (together with ultrasonic drive unit 50) relative to housing 130.

The proximal end of the end effector 180 of the second acoustic portionmay be detachably coupled to the mounting device 84 of the ultrasonicdrive unit 50 near an anti-node as described above. The end effector 180may have a length substantially equal to an integer number of one-halfsystem wavelengths (nλ/2). The end effector 180 may be fabricated from asolid core shaft constructed out of material which propagates ultrasonicenergy efficiently, such as a titanium alloy (e.g., Ti-6Al-4V) or analuminum alloy. It is contemplated that the end effector 180 canalternatively be fabricated from any other suitable material.

As described, the end effector 180 may include a waveguide 181. Thewaveguide 181 may be substantially semi-flexible. It will be recognizedthat, the waveguide 181 can alternatively be substantially rigid or maycomprise a flexible wire. The waveguide 181 may be configured to amplifythe mechanical vibrations transmitted through the waveguide to the bladeas is well known in the art. The waveguide 181 may further have featuresto control the gain of the longitudinal vibration along the waveguide181 and features to tune the waveguide to the resonant frequency of thesystem.

It will be recognized that the end effector 180 may have any suitablecross-sectional dimension. For example, the end effector 180 may have asubstantially uniform cross-section or the end effector 180 may betapered at various sections or may be tapered along its entire length.

Referring now to FIG. 3 , the waveguide 181 portion of the end effector180 is shown to comprise a first section 182, a second section 184, anda third section 186. The first section 182 may extend distally from theproximal end of the end effector 180, and has a substantially continuouscross-section dimension. The first section 182 may include at least oneradial hole or aperture 188 extending diametrically therethrough,substantially perpendicular to the axis of the end effector 180. Theaperture 188 may be positioned at a node, but may be otherwisepositioned. It will be recognized that the aperture 188 may have anysuitable depth and may be any suitable shape. The aperture 188 isconfigured to receive a connector pin member which connects the waveguide 181, the tubular actuating member 170, and the tubular outersheath 160 together for conjoint, indexed rotation relative to apparatushousing 130.

The second section 184 of the wave guide 181 extends distally from thefirst section 182. The second section 184 preferably also has asubstantially continuous cross-section. The diameter of the secondsection 184 may be smaller than the diameter of the first section 182and larger than the diameter of the third section 186. As ultrasonicenergy passes from the first section 182 of the end effector 180 intothe second section 184, narrowing of the second section 184 will resultin an increased amplitude of the ultrasonic energy passing therethrough.

The third section 186 extends distally from the distal end of the secondsection 184. The third section 186 also has a substantially continuouscross-section. The third section 186 also may include small diameterchanges along its length. According to various embodiments, thetransition from the second section 184 to the third section 186 may bepositioned at an anti-node so that the diameter change in the thirdsection does not bring about an increase in the amplitude of vibration.

The third section 186 may have a plurality of grooves or notches (notshown) formed in its outer circumference. The grooves may be located atnodes of the end effector 180 to act as alignment indicators for theinstallation of a damping sheath (not shown) and stabilizing siliconerings or compliant supports during manufacturing. A seal may be providedat the distal-most node, nearest the blade 180′, to abate passage oftissue, blood, and other material in the region between the waveguideand actuating member 170.

The blade 180′ of the end effector 180 may be integral therewith andformed as a single unit. The blade 180′ may alternately be connected bya threaded connection, or by a welded joint. According to variousembodiments, the blade 180′ may be mechanically sharp or mechanicallyblunt. The distal end of the blade 180′ is disposed near an anti-node inorder to tune the acoustic assembly to a preferred resonant frequency f₀when the acoustic assembly is not loaded by tissue. When the transducerassembly is energized, the distal end of the blade 180′ is configured tomove longitudinally in the range of, for example, approximately 10-500microns peak-to-peak, and preferably in the range of about 10 to about100 microns at a predetermined vibrational frequency f₀.

In accordance with the illustrated embodiment, the blade 180′ may becylindrical for cooperation with the associated clamping mechanism ofthe clamp coagulator 120. The end effector 180 may receive suitablesurface treatment, as is known in the art.

FIG. 4 illustrates one embodiment of a clamping mechanism that may beused with the surgical instrument shown in FIG. 1 . The clampingmechanism may be configured for cooperative action with the blade 180′of the end effector 180. The clamping mechanism includes a pivotallymovable clamp arm 190, which is pivotally connected at the distal endthereof to the distal end of outer tubular sheath 160. The clamp arm 190includes a clamp arm tissue pad 192, preferably formed from TEFLON® orother suitable low-friction material, which is mounted for cooperationwith the blade 180′, with pivotal movement of the clamp arm 190positioning the clamp pad 192 in substantially parallel relationship to,and in contact with, the blade 180′. By this construction, tissue to beclamped is grasped between the tissue pad 192 and the blade 180′. Thetissue pad 192 may be provided with a sawtooth-like configurationincluding a plurality of axially spaced, proximally extending grippingteeth 197 to enhance the gripping of tissue in cooperation with theblade 180′.

Pivotal movement of the clamp arm 190 with respect to the blade 180′ iseffected by the provision of at least one, and preferably a pair oflever portions 193 of the clamp arm 190 at the proximal end thereof. Thelever portions 193 are positioned on respective opposite sides of theend effector 180 and blade 180′, and are in operative engagement with adrive portion 194 of the reciprocal actuating member 170. Reciprocalmovement of the actuating member 170, relative to the outer tubularsheath 160 and the end effector 180, thereby effects pivotal movement ofthe clamp arm 190 relative to the blade 180′. The lever portions 193 canbe respectively positioned in a pair of openings defined by the driveportion 194, or otherwise suitably mechanically coupled therewith,whereby reciprocal movement of the actuating member 170 acts through thedrive portion 194 and lever portions 193 to pivot the clamp arm 190.

FIG. 5 illustrates a cut-away view of one embodiment of the surgicalinstrument shown in FIG. 1 , while FIG. 6 illustrates various internalcomponents of one embodiment of the surgical instrument shown in FIG. 1. FIG. 7 illustrates one embodiment of a drive yoke, and FIG. 8illustrates one embodiment of a drive collar of the surgical instrumentshown in FIG. 1 . In the embodiment illustrated in FIGS. 3 and 5-8 ,reciprocal movement of the actuating member 170 is effected by theprovision of a drive collar 200 mounted on the proximal end of theactuating member 170 for conjoint rotation. The drive collar 200 mayinclude a pair of diametrically opposed axially extending arms 202 eachhaving a drive lug 204, with the drive lugs 204 being biased by the arms202 into engagement with suitable openings 206 defined by the proximalportion of tubular actuating member 170. Rotation of the drive collar200 together with the actuating member 170 is further effected by theprovision of a pair of keys 208 diametrically engageable with suitableopenings 210 defined by the proximal end of the actuating member 170. Acircumferential groove 211 on the actuating member 170 receives anO-ring 211′ (FIG. 3 ) for engagement with the inside surface of outersheath 160.

Rotation of the actuating member 170 together with the tubular outersheath 160 and inner end effector 180 is provided by a connector pin 212extending through these components of the instrument 120. The tubularactuating member 170 defines an elongated slot 214 through which theconnector pin 212 extends to accommodate reciprocal movement of theactuating member relative to the outer tubular sheath and the innerwaveguide.

A rotation knob 216 mounted on the outer tubular sheath facilitatesrotational positioning of the elongated portion 150 with respect to thehousing 130 of the clamp coagulator instrument 120. Connector pin 212preferably joins the knob 216 together with the sheath 160, member 170,and the end effector 180 for rotation as a unit relative to the housing130. In the embodiment, hub portion 216′ of the rotation knob 216 actsto rotatably mount the outer sheath 160, the actuating member 170, andthe end effector 180 (as a unit with the knob 216), on the housing 130.

The drive collar 200 provides a portion of the clamp drive mechanism ofthe instrument 120, which effects pivotal movement of the clamp arm 190by reciprocation of the actuating member 170. The clamp drive mechanismfurther includes a drive yoke 220 which is operatively connected with anoperating lever 222, with the operating lever thus interconnected withthe reciprocal actuating member 170 via drive yoke 220 and drive collar200. The operating lever 222 is pivotally connected to the housing 130of the apparatus (by a pivot mount 223) for cooperation in ascissors-like fashion with a handgrip portion 224 of the housing.Movement of the lever 222 toward the handgrip portion 224 translates theactuating member 170 proximally, thereby pivoting the clamp arm 190toward the blade 180′.

Operative connection of the drive yoke 220 with the operating lever 222is provided by a spring 226, preferably comprising a compression coilspring 226. The spring 226 fits within a spring slot 228 defined by thedrive yoke 220, which in turn is positioned between a pair of springretainer flanges 230 of the operating lever 222. The drive yoke 220 ispivotally movable with respect to the spring flanges 230 (about pivotmount 223 of housing 130) in opposition to the compression coil spring,which bears against the surfaces of the spring slots defined by each ofthe spring flanges 230. In this manner, the force which can be appliedto the actuating member 170, by pivotal movement of the operating lever222 acting through the drive yoke 220 and the drive collar 200, islimited by the force with which the spring 226 bears against the springflanges 230. Application of excessive force results in pivotaldisplacement of the drive yoke 220 relative to the spring flanges 230 ofthe operating lever 222 in opposition to spring 226. Stop portions ofthe housing 130 limit the travel of the operating lever 222 to preventexcessive compression of spring 226. In various embodiments, the forceapplied to the actuating member 170 may be limited by one or moresprings (not shown) operatively positioned between the drive collar 200and the member 170. For example, one or more cylindrical springs, suchas a wave springs, may be used. An example embodiment utilizing a wavespring in this manner is described in U.S. Pat. No. 6,458,142, which isincorporated herein by reference.

Indexed rotational positioning of the elongated portion 150 of thepresent clamp coagulator instrument 120 may be provided by the provisionof a detent mechanism incorporated into the clamp drive mechanism of theinstrument 120. Specifically, the drive collar 200 may include a pair ofaxially spaced apart drive flanges 232. A detent-receiving surface maybe provided between the drive flanges 232, and may define a plurality ofcircumferentially spaced teeth 234. The teeth 234 may definedetent-receiving depressions generally about the periphery of the drivecollar 200. In the embodiment illustrated in FIG. 7 , twelve (12) of theteeth 234 are provided, thereby providing indexed positioning of theelongated portion 150 of the apparatus at 30° intervals relative to thehousing 130 of the apparatus.

Indexed rotational movement may be further achieved by the provision ofat least one, and preferably a pair, of diametrically opposed detents236 respectively provided on cantilevered yoke arms 238 of the driveyoke 220. By this arrangement, the yoke arms 238 are positioned betweenthe drive flanges 232 for engagement with the confronting surfacesthereof, and bias the detents 236 into engagement with the drive collar200. Indexed relative rotation is thus achieved, with the detents 236 ofthe yoke arms 238 cooperating with the drive flanges 238 for effectingreciprocation of the actuating member 170. According to variousembodiments, the drive yoke 220 may be formed from suitable polymericmaterial, with the biasing force created by the yoke arms 238 acting onthe detents 236 thereof cooperating with the radial depressions definedby the drive collar to resist relative rotational torque less than about5 to 20 inch-ounces. Accordingly, the elongated portion 150 of the clampcoagulator instrument 120 is maintained in any of its selected indexedrotational positions, relative to the housing 130, unless a torque isapplied (such as by the rotation knob 216) exceeding this predeterminedtorque level. A snap-like indexing action is thus provided.

Rotation of the elongated proportion 150 of the present clamp coagulatorinstrument 120 may be effected together with relative rotationalmovement of ultrasonic drive unit 50 with respect to housing 130. Inorder to join the elongated portion 150 to the ultrasonic drive unit 50in ultrasonic-transmitting relationship, the proximal portion of theouter tubular sheath 160 may be provided with a pair of wrench flats 240(FIG. 3 ). The wrench flats allow torque to be applied by a suitabletorque wrench or the like to thereby permit the end effector 180 to bejoined to the ultrasonic drive unit 50. The ultrasonic drive unit 50, aswell as the elongated portion 150, are thus rotatable, as a unit, bysuitable manipulation of the rotation knob 216, relative to the housing130 of the apparatus. The interior of housing 130 is dimensioned toaccommodate such relative rotation of the drive unit 50.

FIG. 9 illustrates one embodiment of a surgical system 250 including asurgical instrument 251 having single element end effector 256. Thesystem 250 may include a transducer assembly 252 coupled to the endeffector 256 and a sheath 254 positioned around the proximal portions ofthe end effector 256 as shown. The transducer assembly 252 and endeffector 256 may operate in a manner similar to that of the transducerassembly 50 and end effector 180 described above to produce ultrasonicenergy that may be transmitted to tissue via a blade 256′.

FIG. 10 illustrates a block diagram of one embodiment of a surgicaldevice 1000, which may be configured with temperature feedbackfunctionality. For example, the control circuit 1002 may adjust acurrent amplitude of an electrical signal provided by the generator 1004to the transducer 1006 in response to changes in a vibration frequencyof the end effector 1008. According to various embodiments, when thevibration frequency of the end effector 1008 drops, the amplitude of theelectrical signal may be reduced. This may allow the surgical device1000 to maintain the end effector 1008 at a relatively constanttemperature and, thus give the device 1000 more uniform performance.

During surgical procedures, the end effector 1008 may be brought intocontact with tissue and vibrated to cut and/or coagulate the tissue, asdescribed above. When this occurs, friction between the end effector1008 and the tissue may cause the temperature of the end effector 1008to rise. As the temperature of the end effector 1008 rises, its materialproperties may change, causing changes to the device 1000 as a whole.For example, as the temperature of the end effector 1008 rises, therelationship between the displacement of the end effector 1008 and thecurrent amplitude of the electrical signal may change such that thedisplacement of the end effector 1008 increases without a correspondingincrease in the current amplitude. Also, as the temperature of the endeffector 1008 rises, the resonant vibration frequency of the endeffector 1008 may be reduced. For example, the changed materialproperties of the end effector 1008 may reduce the resonant frequency ofthe device 1000. As a result, the generator 1004 may reduce thefrequency of the electrical drive signal bringing about a parallelreduction in the driven vibration frequency of the end effector 1008.

The control circuit 1002 may monitor the electrical signal provided bythe generator 1004. As described, a decrease in the frequency of theelectrical signal may indicate an increase in the temperature of the endeffector 1008 as well as an increase in its displacement. When thecontrol circuit 1002 senses a decrease in the frequency of theelectrical signal it may command the generator 1004 to reduce thecurrent amplitude of the electrical signal. The current amplitude of theelectrical signal may be reduced by an amount suitable to keep thefrequency of the end effector 1008 substantially constant resulting in asubstantially constant temperature of the end effector 1008. The amountof current amplitude change necessary to compensate for a givenfrequency change may be determined by any suitable experimental ortheoretical method.

It will be appreciated that the device 1000 may be physically embodiedas any suitable ultrasonic device or system including, for example, thesystems 10 and 250 described above. The control circuit 1002 may beembodied as any suitable analog or digital circuit. For example, thecontrol circuit 1002 may comprise a processor, for example, a digitalsignal processor (DSP).

In addition to, or instead of the temperature feedback functionalitydescribed above, one embodiment of the device 1000 shown in FIG. 10 maybe configured to detect cavitation, wherein the acoustic cavitationsignal is transferred from the tissue to the end effector 1008. This mayprovide the clinician with information regarding the state of thetissue. For example, before the tissue is desiccated, substantially allof the water present in the tissue may be removed, either by evaporationor boiling. As water is evaporated or boiled, it may generatecavitations in the tissue. Detecting the presence of these cavitationsmay allow the device 1000 to give the clinician an indication that thetissue is, or is about to be, desiccated. Other tissue transitionsoccurring during cutting and/or coagulation may be indicated by variousother cavitations.

Tissue cavitations originating from tissue in contact with the endeffector 1008 (and/or from fluid included within the tissue) may affectthe vibration of the end effector 1008, and accordingly the electricalsignal between the generator 1004 and the transducer 1006. As describedabove, the piezoelectric elements (not shown) may generate motion inresponse to an electrical charge. Also, piezoelectric elements may workin reverse and generate and/or modify an electrical charge in responseto motion. Accordingly, tissue cavitations transferred to the endeffector 1008 may be, in turn, transferred to the piezoelectric elementsof the transducer 1006. This may cause the piezoelectric elements togenerate charges that modify the electrical signal between the generator1004 and the transducer 1006 in a manner proportional to the tissuecavitations. Isolating the portion of the electrical signal due to thetissue cavitations may indicate the presence of tissue cavitations, aswell as their dominant frequency/frequencies, and other information.

The portion of the electrical signal due to tissue cavitation may beisolated in any suitable way. For example, the control circuit 1002 mayinclude a filter circuit (not shown) to filter the drive frequency andany harmonics thereof from the electrical signal. The remainingcomponents of the electrical signal may be due to tissue cavitation. Thefilter circuit may comprise any suitable analog or digital filter.

Many tissue cavitations are of a relatively short duration, andtherefore have a relatively wide frequency content. Accordingly, thetissue cavitations may not be apparent at any distinct frequencies andmay instead serve to excite the end effector 1008 at its resonantfrequency (e.g., the vibration frequency) and the harmonics thereof. Tohandle this scenario, the control circuit 1002 may include a processoror other functionality to compare the electrical signal to a comparisonelectrical signal measured when the end effector 1008 is unloaded, ornot in contact with tissue. Differences between the measured electricalsignal and the comparison electrical signal may indicate the presence oftissue cavitations. When the control circuit 1002 senses the presence oftissue cavitations, it may communicate this to the clinician anysuitable method including, for example, by using a light, a displayand/or an audible signal.

FIG. 11 shows a graph 1100 illustrating results of an example test ofone embodiment of a surgical device. In the example test, externalcavitations are identified by analyzing the frequency content of anelectrical signal between a transducer and an end effector. In the test,an LCS14C end effector was used in conjunction with a HP054 transducerand a GEN 300 generator operated at a nominal drive frequency of 55.5kHz. All of these components are available from Ethicon Endo Surgery,Inc. A control trial was performed by energizing the end effector in airat a level 5 power setting for a period of 100 milliseconds. During thistime, the electrical signal between the transducer and generator wasmonitored with an AGILENT Oscilloscope Model 5483D. For eachexperimental trial, the end effector was placed in a plastic beakerfilled with 400 cc of fresh tap water. The end effector was thenenergized at a given power level for a period of 100 milliseconds whilethe electrical signal between the transducer and generator was monitoredwith the oscilloscope. Three experimental trials were run at generatorsettings of 1, 3 and 5 respectively.

The graph 1100 illustrates the amplitudes of low-Q peaks in theelectrical signal observed during the control and experimental trials atthe drive frequency and at two harmonics of the drive frequency. Line1102 illustrates the drive frequency of 55.5 kHz, line 1104 illustratesa first harmonic at 45 kHz, and line 1106 illustrates a second harmonicat 63 kHz. It can be seen that the amplitude of the low-Q peak at thedrive frequency was markedly higher during the experimental trials thanduring the control trial. Likewise, the amplitude of the low-Q peaks atthe harmonics was higher during the experimental trials. It is believedthat these increased amplitudes at the drive frequency 1102 and theharmonics 1104, 1106 were due to cavitations caused when dissolved gasin the tap water was released by the vibration of the end effector. Insupport of this conclusion, it is noted that when the tap water was notchanged between trials, the low-Q peaks were significantly smaller,suggesting that all of the dissolved gas had been released. When the endeffector encounters tissue cavitations, similar effects would beapparent in the low-Q peaks at the drive and harmonic frequencies of thedevice.

In addition to, or instead of the functionality described above, thedevice 1000 shown in FIG. 10 may have functionality for monitoringchanges in the frequency of the end effector 1008. For example, thecontrol circuit 1002 may monitor the vibration frequency of the endeffector to detect changes. Changes in end effector frequency mayindicate changes in tissue that is in contact with the end effector.FIG. 12 shows a chart 1200 illustrating a relationship between endeffector frequency 1202 and end effector temperature 1204 over thecoagulation and cutting process. The horizontal axis 1201 representstime while the vertical axis 1203 represents temperature with respect tothe curve 1204 and end effector vibration frequency with respect to thecurve 1202. The vertical line 1206 represents the approximate beginningof tissue coagulation (e.g., the denaturing of collagen describedabove). Vertical line 1208 represents the approximate beginning ofdesiccation and incipient transection.

Over the course of the cutting/coagulation process shown in chart 1200,the temperature curve 1204 increases. Prior to the beginning ofcoagulation 1206, the temperature curve 1204 increases sharply. Betweencoagulation 1206 and desiccation 1208, the increase in the slope of thetemperature versus time curve 1204 is reduced. After desiccation 1208,the temperature curve 1204 again begins to increase more rapidly. Theend effector frequency curve 1202 may mirror the temperature curve 1204.For example, the frequency curve 1202 may decrease rapidly prior to thebeginning of coagulation 1206. At the beginning of coagulation 1206, thefrequency curve 1202 continues to decrease, but does so less rapidly,demonstrating a knee feature 1210. At around the onset of desiccation1208, the frequency curve 1208 may begin to decrease more rapidly.

According to various embodiments, the control circuit 1002 may beprogrammed to recognize the changes in the rate of decrease in thefrequency curve 1202 to derive an indication of when tissue has begun tocoagulate, and when it has begun desiccation. In one embodiment, thecontrol circuit 1002 may monitor the vibration frequency of the endeffector 1008 by monitoring the frequency of the electrical signalbetween the generator 1004 and transducer 1006. It will be appreciatedthat these two frequencies may be the same. When the control circuit1002 senses that the rate of decrease of the end effector frequency hasdeclined (e.g., the curve 1202 has reached the knee feature 1210), thecontrol circuit 1002 may generate an indication that coagulation hasbegun. When the control circuit 1002 senses that the rate of decrease ofthe end effector frequency has again increased, it may indicate thebeginning of desiccation. The various indications may be communicated tothe clinician by the device 1000 according to any suitable methodincluding, for example, a light, a display and an audible signal.According to various embodiments, the control circuit 1002 mayde-energize the end effector 1008, or reduce its amplitude of vibration,in response to a transition to coagulation or to desiccation. This mayallow the clinician to inspect the tissue before coagulation and/ordesiccation to ensure that the procedure is proceeding satisfactorily.

According to various embodiments, the device 1000 of FIG. 10 may combinefrequency change functionality with tissue cavitation sensingfunctionality to indicate the state of tissue in contact with the endeffector 1008. For example, although the frequency curve 1202 shown inFIG. 12 illustrates a knee feature 1210 at the onset of coagulation1206, its rate of frequency change may transition more gradually at theonset of desiccation 1208. Accordingly, it may be difficult toaccurately identify the onset of desiccation 1208 by monitoring the endeffector frequency alone. Tissue cavitations, on the other hand, aremost common at about the onset of desiccation 1208. For example, aswater is evacuated from the tissue, it may boil violently, causingcavitations. Accordingly, the control circuit 1002 may be configured toidentify the onset of coagulation 1206 by identifying the knee 1210 inthe end effector frequency curve 1202, as described above. Also, thecontrol circuit 1002 may be configured to identify the onset ofdesiccation 1208 by identifying tissue cavitations, for example, inconjunction with an increase in the rate of reduction of the endeffector frequency curve 1202. Again, the various indications may becommunicated to the clinician by the device 1000 according to anysuitable method including, for example, a light, a display and anaudible signal. Also, the device 1000 may be de-energized, or thevibration frequency of the end effector 1008 reduced, upon a transitionto coagulation or desiccation, as described above.

FIG. 13 illustrates a block diagram of one embodiment of a surgicaldevice 1300 configured to derive end effector feedback considering acoefficient of collagen denaturation (CCD). The CCD may represent anamount of friction between the end effector 1308 and a portion of tissue(not shown). Analysis of a CCD curve taken over the course of a cuttingand/or coagulation procedure may provide information about the progressof the cutting and coagulation as well as information about the tissueportion including, for example, its thickness and outside diameter.

According to various embodiments, the CCD may be calculated as afunction of variables, for example, including: (i) power provided to theend effector 1308; (ii) the vibration frequency of the end effector1308; (iii) the displacement of the end effector 1308 over a cycle; and(iv) a clamp force applied to the region of tissue between the clampingmechanism 1310 and the end effector. The clamping mechanism 1310 itselfmay be any suitable mechanism for clamping or otherwise exerting a forceon the tissue region against the end effector. According to variousembodiments, the clamping mechanism 1310 may be similar to the clampingmechanism 190 described above. Values for the above variables over timemay be found by the control circuit 1302 of the device 1300. Forexample, the power provided to the end effector 1308 may be found byconsidering the electrical signal between the generator 1304 and thetransducer 1306 while the end effector 1308 is under load (e.g., incontact with the region of tissue). The displacement per cycle of theend effector 1308 may be a function of the current amplitude of theelectrical signal. Also, as described above, the vibration frequency ofthe end effector 1308 may be substantially similar to that of theelectrical signal.

The clamp force of the end effector 1308 and clamping mechanism 1310 maybe found according to any suitable method. For example, according tovarious embodiments, the clamping mechanism 1310 may be driven by anelectric motor. For example, referring to the embodiment shown in FIG. 2, the reciprocal actuating member 170 may be translated distally andproximally by the motor 1312. In this embodiment, the clamping forcebetween the clamping mechanism 1310 and the end effector 1308 may bederived from a drive electrical signal provided to the motor 1312. Forexample, the current amplitude of the drive electrical signal mayindicate the clamping force. According to various embodiments, the clampforce may be derived from a sensor 1314 in communication with thecontrol circuit 1302. The sensor may be placed at any suitable locationin communication with the end effector 1308, clamping mechanism 1310and/or a portion of the device handpiece (not shown in FIG. 13 ). Theembodiment shown in FIG. 4 illustrates one example of a sensor 1316positioned between the clamp arm tissue pad 192 and clamp arm 190. Also,the embodiment shown in FIG. 2 illustrates a sensor 1318 positionedbetween a portion of the operating lever 222 and drive collar 200. Inone embodiment, the clamp force may be considered a constant andfactored into the CCD calculations as such.

The device 1300 may utilize the CCD curve to sense when the portion oftissue enters the coagulation and desiccation stages. FIG. 14 shows agraph illustrating a CCD curve 1402 over a full coagulating and cuttingtransaction. The CCD curve 1402 was derived with an ultrasonicinstrument having a solid core end effector powered by a GEN03 generatordevice available from Ethicon Endo Surgery, Inc. The power of thegenerator was set to level three (3); the end effector 1408 displacementwas set to 55 microns; the end effector vibration frequency wasconfigured at 55.5 kHz; and a clamping force of 2 pounds was utilized.The curve 1402 may be divided into three regions. A first region 1408may correspond to times before the onset of coagulation 1404 and mayhave a substantially negative slope. A second region 1410 may correspondto times between the onset of coagulation 1404 and the onset ofdesiccation 1406 and may have a substantially neutral slope. A thirdregion 1412 may correspond to times after the onset of desiccation 1406and may have a substantially positive slope. According to variousembodiments, the control circuit may monitor the slope of the CCD curve1402 to determine the state of the tissue portion. Transitions tocoagulation or to desiccation may be indicated to the clinicianaccording to any suitable method including, for example, a light, adisplay and/or an audible signal. Also, as described, the controlcircuit 1302 may de-energize the end effector 1308 in response to atransition to coagulation or to desiccation.

The CCD curve 1402 also may be utilized by the control circuit 1302 todetermine other features of the tissue portion including, for example,its outside diameter and thickness. It will be appreciated that thetissue portion may be a solid portion of tissue, or may define a lumen(e.g., an artery, vein or other tubular tissue time). FIG. 15 shows agraph illustrating a coefficient of collagen denaturation curve 1502.The curve 1502 was derived over the coagulation and desiccation of aCarotid artery utilizing an ultrasonic instrument having a solid coreend effector powered by a GEN03 generator device. The power of thegenerator was set to level five (5). The end effector 1408 displacementwas set to 55 microns; the end effector vibration frequency wasconfigured at 55.5 kHz; and a clamping force of 2 pounds was utilized.The CCD curve 1502 has been broken into nine regions 1504, 1506, 1508,1510, 1512, 1514, 1516, 1518 and 1520 having a substantially constantslope.

Various properties of each of the nine regions of the CCD curve 1402 maycorrelate to properties of the tissue portion such as the outer diameterand thickness. In one example experiment, fourteen carotid arteries ofvarious diameters were coagulated and cut with an ultrasonic instrumenthaving a solid core end effector powered by a GEN03 generator device.Table 1 below shows the Outside Diameter and Wall Thickness of thecarotid arteries as well as the Clamp Force and Power Level used. ThePolynomial Fit column lists the exponent of the polynomial fit to thefirst region 1504 of the CCD curve for each trial. The Normalized CCDvalue shows the CCD value for each trial normalized by dividing eachindividual CCD value by the CCD value at the end of the first region1504.

TABLE 1 Outside Diam- Wall Clamp Power eter Thick- Polynomial NormalizedTrial Force Level (in.) ness Fit CCD Value 1 0.4 3 0.169 0.042 .01811.2826 2 1 3 0.169 0.042 0.254 * 3 0.4 5 0.117 0.04 0.227 * 4 1 5 0.1170.04 0.251 * 5 0.4 4 0.146 0.042 0.251 1.16738 6 1 4 0.146 0.042 0.3611.47 7 0.4 4 0.136 0.05 0.266 1.14 8 1 4 0.136 0.05 1.231 1.23 9 0.7 30.094 0.045 1.765 1.05 10 0.7 5 0.094 0.045 0.744 1.35 11 0.7 3 0.1560.045 0.15 1.1 12 0.7 5 0.156 0.045 0.214 1.49 13 0.7 4 0.119 0.0350.791 1.27 14 0.7 4 0.119 0.035 0.295 1.23

FIG. 16 shows a series of curves 1602, 1604, 1606, 1608 illustratingrelationships between the normalized value of the first point of thefirst region of the CCD curve clamp force, power level, outside diameterand wall thickness for the trials shown in Table 1. The degree of theslope of the curves 1602, 1604, 1606, 1608 may indicate the degree ofcorrelation between the corresponding variable and the normalized valueof the first point of the first region of the CCD curve. It can be seenthat all of the curves 1602, 1604, 1606 and 1608 have non-zero slopes,and therefore all of their corresponding variables are correlated to theCCD curve. A mathematical model, such as a quadratic model, may be fitto the results of trials, such as those shown in Table 1, to derive oneor more equations relating the normalized value of the first point ofthe first region of the CCD curve, the clamp force, the power level,outside diameter and wall thickness.

Referring back to the embodiment shown in FIG. 13 , the control circuit1302 may monitor a CCD curve generated as the device 1300 coagulatesand/or cuts the tissue portion. Upon identifying a region of the CCDcurve having a substantially similar slope, the control circuit 1302 mayderive a property describing the region including, for example, a slopeof the region, a normalized value of the curve in the region and/or alength of the first region. The control circuit 1302 may then derive aproperty of the tissue portion including, for example an outsidediameter of the tissue portion or a thickness of the tissue portion. Thetissue properties may be derived according to any suitable method. Forexample, mathematical models relating region properties to tissueproperties may be developed, for example, as described above. Thecontrol circuit 1302 may utilize a predetermined mathematical model torelate the region property and tissue property. Also, according tovarious embodiments, look-up tables may be generated relating regionproperties to tissue properties.

FIG. 17 illustrates one embodiment of an end effector 1700 for asurgical device including radial mode transducers 1702, 1704, 1706. Whenexcited by an electrical signal (e.g., from a generator) the radial modetransducers 1702, 1704, 1706 may generate ultrasonic vibrationsperpendicular to a longitudinal axis 1710. The ultrasonic vibrations mayhave anti-nodes at the radial surfaces of the transducers 1702, 1704,1706. As a result, the entire radial surface of the end effector 1700may be active for coagulating and cutting tissue. A central member 1708may extend along the longitudinal axis 1710 and may serve as anelectrode for some or all of the radial mode transducer 1702, 1704,1706. Additionally the outer radial surface of the radial modetransducers 1702, 1704, 1706 may be coated with an electricallyconductive substance or alternatively may be enclosed in a metal tubularsheath, either of which may serve as an electrode. Although multipletransducers 1702, 1704, 1706 are shown, it will appreciated that someembodiments may include only one radial mode transducer.

FIG. 18 illustrates one embodiment of the end effector 1700 of FIG. 17installed on a surgical instrument 1800 including a clamp arm 1802.Additional radial mode transducers 1701 and 1703 are shown, although itwill be appreciated that any suitable number of transducers may be used.The clamp arm 1802 may be pivotable toward the end effector 1700 similarto the way that clamp arm 190 is pivotable toward end effector 180 inthe embodiment shown in FIG. 4 . According to various embodiments, thecentral member 1708 of the end effector 1700 may be flexible. This mayallow the various radial mode transducers 1702, 1704, 1706 to flexrelative to each other. FIG. 19 illustrates one embodiment of the endeffector 1700 of FIG. 17 where the central member 1708 is flexible. Theflexibility of the central member 1708 may allow the different radialmode transducers, here 1706 and 1704, to flex relative to one anotherleading to a flexible and articulatable end effector 1700. Articulationof the end effector 1700 may be brought about in any suitable manner.For instance, the flexible central member 1708 may define a centrallumen (not shown). Metal wires (not shown) may run within the centralmember 1708 on opposing sides of the central lumen. An articulation knobor other articulate implement near a handle portion of the instrumentmay be used to retract one of the metal wires. When a metal wire isretracted, it may cause the flexible central member 1708, and thereforethe end effector 1700 to articulate in the direction of the retractedwire. For example, if a wire on the right side of the central member1708 is retracted, then the end effector 1700 may articulate to theright. It will be appreciated that this is but one example of anarticulation mechanism and that any suitable articulation method may beused.

FIGS. 20-21 illustrate one embodiment of the end effector 1700 of FIG.17 including a transducer 2002 defining a concavity 2004. The transducer2002 may utilize the concavity 2004 to direct ultrasonic energy totissue that is not in direct physical contact with the transducer 2002or the end effector 1700. For example, the concavity of the transducer2002 may serve to focus ultrasonic energy to points 2006. According tovarious embodiments, the concavity 2004 may extend radially around thetransducer 2002, as shown in the embodiment of FIG. 21 . Accordingly,the focal point 2006 extends radially around the transducer 2002 forminga toroid.

The devices disclosed herein can be designed to be disposed of after asingle use, or they can be designed to be used multiple times. In eithercase, however, the device may be reconditioned for reuse after at leastone use. Reconditioning can include any combination of the steps ofdisassembly of the device, followed by cleaning or replacement ofparticular elements, and subsequent reassembly. In particular, thedevice may be disassembled, and any number of particular elements orcomponents of the device may be selectively replaced or removed in anycombination. Upon cleaning and/or replacement of particular components,the device may be reassembled for subsequent use either at areconditioning facility, or by a surgical team immediately prior to asurgical procedure. Those skilled in the art will appreciate thatreconditioning of a device may utilize a variety of techniques fordisassembly, cleaning/replacement, and reassembly. Use of suchtechniques, and the resulting reconditioned device, are all within thescope of the present application.

Preferably, the various embodiments described herein will be processedbefore surgery. First, a new or used instrument is obtained and ifnecessary cleaned. The instrument can then be sterilized. In onesterilization technique, the instrument is placed in a closed and sealedcontainer, such as a plastic or TYVEK® bag. The container and instrumentare then placed in a field of radiation that can penetrate thecontainer, such as gamma radiation, x-rays, or high-energy electrons.The radiation kills bacteria on the instrument and in the container. Thesterilized instrument can then be stored in the sterile container. Thesealed container keeps the instrument sterile until it is opened in themedical facility.

It is preferred that the device is sterilized prior to surgery. This canbe done by any number of ways known to those skilled in the artincluding beta or gamma radiation, ethylene oxide, steam.

Although various embodiments have been described herein, manymodifications and variations to those embodiments may be implemented.For example, different types of end effectors may be employed. Also,where materials are disclosed for certain components, other materialsmay be used. The foregoing description and following claims are intendedto cover all such modification and variations.

Any patent, publication, or other disclosure material, in whole or inpart, that is said to be incorporated by reference herein isincorporated herein only to the extent that the incorporated materialsdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this disclosure. As such, and to theextent necessary, the disclosure as explicitly set forth hereinsupersedes any conflicting material incorporated herein by reference.Any material, or portion thereof, that is said to be incorporated byreference herein, but which conflicts with existing definitions,statements, or other disclosure material set forth herein will only beincorporated to the extent that no conflict arises between thatincorporated material and the existing disclosure material.

What is claimed is:
 1. An ultrasonic surgical instrument, comprising: anultrasonic blade; an ultrasonic transducer operably coupled to theultrasonic blade, wherein the ultrasonic transducer is configured totransmit ultrasonic vibrations to the ultrasonic blade based on a drivesignal; and a control circuit configured to: provide the drive signal tothe ultrasonic transducer; monitor a vibration frequency of the drivesignal; and modify the drive signal based on a change in the vibrationfrequency of the drive signal.
 2. The ultrasonic surgical instrument ofclaim 1, wherein the change in the vibration frequency of the drivesignal comprises a reduction in a rate of decrease of the vibrationfrequency of the drive signal.
 3. The ultrasonic surgical instrument ofclaim 2, wherein the change in the vibration frequency of the drivesignal corresponds to an onset of tissue coagulation.
 4. The ultrasonicsurgical instrument of claim 3, wherein the change in the vibrationfrequency of the drive signal is a first change in the vibrationfrequency of the drive signal, wherein the control circuit is furtherconfigured to detect a second change in the vibration frequency of thedrive signal after the first change in the vibration frequency of thedrive signal.
 5. The ultrasonic surgical instrument of claim 4, whereinthe second change in the vibration frequency of the drive signalcomprises an increase in the rate of decrease of the vibration frequencyof the drive signal.
 6. The ultrasonic surgical instrument of claim 5,wherein the second change in the vibration frequency of the drive signalcorresponds to an onset of tissue desiccation.
 7. The ultrasonicsurgical instrument of claim 1, wherein the change in the vibrationfrequency of the drive signal comprises an increase in a rate ofdecrease of the vibration frequency of the drive signal, and wherein thechange in the vibration frequency of the drive signal corresponds to anonset of tissue desiccation.
 8. The ultrasonic surgical instrument ofclaim 1, wherein modifying the drive signal comprises changing acharacteristic of the drive signal.
 9. The ultrasonic surgicalinstrument of claim 1, wherein the vibration frequency of the drivesignal is based on a vibration frequency of the ultrasonic blade.
 10. Anultrasonic surgical instrument, comprising: an ultrasonic transducer; anend effector, comprising: a clamp arm; and an ultrasonic blade operablycoupled to the ultrasonic transducer, wherein the clamp arm is movablerelative to the ultrasonic blade to capture tissue; and a controlcircuit configured to: provide a drive signal to the ultrasonictransducer to cause the ultrasonic transducer to transmit ultrasonicvibrations to the ultrasonic blade; monitor a vibration frequency of thedrive signal; and modify the drive signal based on a change in thevibration frequency of the drive signal.
 11. The ultrasonic surgicalinstrument of claim 10, wherein the change in the vibration frequency ofthe drive signal comprises a reduction in a rate of decrease of thevibration frequency of the drive signal.
 12. The ultrasonic surgicalinstrument of claim 11, wherein the change in the vibration frequency ofthe drive signal corresponds to an onset of tissue coagulation.
 13. Theultrasonic surgical instrument of claim 12, wherein the change in thevibration frequency of the drive signal is a first change in thevibration frequency of the drive signal, wherein the control circuit isfurther configured to detect a second change in the vibration frequencyof the drive signal after the first change in the vibration frequency ofthe drive signal.
 14. The ultrasonic surgical instrument of claim 13,wherein the second change in the vibration frequency of the drive signalcomprises an increase in the rate of decrease of the vibration frequencyof the drive signal.
 15. The ultrasonic surgical instrument of claim 14,wherein the second change in the vibration frequency of the drive signalcorresponds to an onset of tissue desiccation.
 16. The ultrasonicsurgical instrument of claim 10, wherein the change in the vibrationfrequency of the drive signal comprises an increase in a rate ofdecrease of the vibration frequency of the drive signal, and wherein thechange in the vibration frequency of the drive signal corresponds to anonset of tissue desiccation.
 17. The ultrasonic surgical instrument ofclaim 10, wherein modifying the drive signal comprises changing acharacteristic of the drive signal.
 18. The ultrasonic surgicalinstrument of claim 10, wherein the vibration frequency of the drivesignal is based on a vibration frequency of the ultrasonic blade.
 19. Anultrasonic surgical instrument, comprising: an ultrasonic transducer; anultrasonic blade operably coupled to the ultrasonic transducer; meansfor providing a drive signal to the ultrasonic transducer to cause theultrasonic transducer to transmit ultrasonic vibrations to theultrasonic blade; means for monitoring a vibration frequency of thedrive signal; and means for modifying the drive signal based on a changein the vibration frequency of the drive signal.
 20. The ultrasonicsurgical instrument of claim 19, wherein the means for modifying thedrive signal comprises changing a characteristic of the drive signal.21. An ultrasonic surgical instrument, comprising: an ultrasonictransducer for use with an ultrasonic blade, wherein the ultrasonictransducer is configured to transmit ultrasonic vibrations to theultrasonic blade based on a drive signal; and a control circuitconfigured to: provide the drive signal to the ultrasonic transducer;determine a vibration frequency of the drive signal; and update thedrive signal based on a change in the vibration frequency of the drivesignal.
 22. The ultrasonic surgical instrument of claim 21, wherein thechange in the vibration frequency of the drive signal comprises areduction in a rate of decrease of the vibration frequency of the drivesignal.
 23. The ultrasonic surgical instrument of claim 22, wherein thechange in the vibration frequency of the drive signal corresponds to anonset of tissue coagulation.
 24. The ultrasonic surgical instrument ofclaim 23, wherein the change in the vibration frequency of the drivesignal is a first change in the vibration frequency of the drive signal,wherein the control circuit is further configured to detect a secondchange in the vibration frequency of the drive signal after the firstchange in the vibration frequency of the ultrasonic blade.
 25. Theultrasonic surgical instrument of claim 24, wherein the second change inthe vibration frequency of the drive signal comprises an increase in therate of decrease of the vibration frequency of the drive signal.
 26. Theultrasonic surgical instrument of claim 25, wherein the second change inthe vibration frequency of the drive signal corresponds to an onset oftissue desiccation.
 27. The ultrasonic surgical instrument of claim 21,wherein the change in the vibration frequency of the drive signalcomprises an increase in a rate of decrease of the vibration frequencyof the drive signal, and wherein the change in the vibration frequencyof the drive signal corresponds to an onset of tissue desiccation. 28.The ultrasonic surgical instrument of claim 21, wherein updating thedrive signal comprises changing a characteristic of the drive signal.29. The ultrasonic surgical instrument of claim 21, wherein thevibration frequency of the drive signal is based on a vibrationfrequency of the ultrasonic blade.